1. Field of the Invention
The present invention relates to a method of forming a metal line layer in a semiconductor device and, more particularly to a method capable of reliably forming a metal line layer by depositing a metal line layer, depositing an insulating film as a hard mask, and then patterning the metal line layer.
2. Discussion of Related Art
Now, a conventional method of forming a metal line layer in a semiconductor device will be described in detail with reference to FIGS. 1A and 1B.
Referring to FIG. 1A, a metal line layer 110 is deposited on a lower oxide film (not shown). The metal line layer 110 may have a multi-layered structure. Then, a photoresist material 120 is deposited and then necessary portions are opened.
Referring to FIG. 1B, dry etching for the metal line layer 110 is dry-etched by using the patterned photoresist material 120 as a mask. However, the photoresist material 120 on the metal line layer 110 may be hardened to form metal polymers 130 during the dry etching process of the metal line layer 110. In practical processes, although these phenomena cannot be identified before the photoresist material 120 is perfectly removed, there are a lot of cases that the metal polymers 130 are not perfectly removed and remain on the metal line layer 110 even after removing the photoresist material 120. In addition, on top portions of the lower oxide film 140, which is exposed after completing the dry etching of the metal line layer, there may be metal residues 132, which induce bridge phenomena in the metal line layer 110.
Furthermore, during the patterning of the metal line layer 110, there may be a lot of losses of the photoresist material in the dry etching process for the metal line layer 110 due to poor selectivity for the photoresist material 120. This may cause attacks on the metal line layer 110 so that the patterns can be deteriorated. Particularly, this kind of problem can be serious to the case that the metal line layer 110 has a multi-layered metal structure including materials such as Ti/TiN.
Therefore, it is really necessary to prepare an effective method for ensuring reliability in the process of forming a metal line layer.